1. Field of the Invention
This invention relates generally to web cleaning devices for cleaning contaminants from a moving surface in a printing apparatus such as an electrostatographic reproduction apparatus. It is particularly suitable for cleaning contaminants off a moving surface in the form of a drum or a belt.
2. Description Relative to the Prior Art
As noted in U.S. Pat. No. 5,075,733, it is well known since the introduction of plain paper desk-top copiers to use a disposable cleaning web for light-duty cleaning of image or other moving members. Typically, a cleaning web of cloth or paper is supplied on a supply spool or bobbin, trained about a pressure roller and taken up on a take-up spool or bobbin. The pressure roller is urged by a spring into contact with the image member to clean the image member according to the surface characteristics of the web and the amount of pressure applied by the pressure roller. The take-up roller is indexed periodically by its own separate motor, or by a substantially reduced drive between it and the main drive on the image forming device, for example, the drive for a photoconductive drum. Still other web cleaning devices are disclosed in U.S. Pat. Nos. 4,110,035 and 4,568,174. The devices disclosed in these latter patents include a path for the web cleaner between supply and take-up that involves the additional use of rollers which add an expense to the web cleaning device.
In order to reduce the costs of web cleaning devices it is known to use a web cleaning device I0 such as shown in FIG. 1 wherein there is schematically shown a fabric cleaning web supply spool or bobbin 12 that is supported within a U-shaped structure 14 so that the supply spool or bobbin 12 does not have its core 13 rotatively mounted and is thus free to move within the U-shaped structure. As shown, the cleaning web material 15 is wound about the supply spool or bobbin in a clockwise direction and then payed out through an opening 11 in the U-shaped structure so that the cleaning web material web is caused to bend about a lip 11a of the opening and then about the bottom 14a of the U-shaped structure and is in tension between the bottom of the U-shaped structure and the take-up spool or bobbin 16. The cleaning web material is then wound in a counterclockwise direction about the take-up spool or bobbin, which is motor driven through a suitable gear reduction. The cleaning web 15 is pressed by the bottom of the U-shaped structure against a moving surface 17 being cleaned to remove contaminants 18, such as toner dust or paper dust therefrom (shown greatly enlarged). The contaminants remain with the fabric and are sealed off by being wrapped in the successive plies of the web as the web is wound on the take-up spool or bobbin. A problem with the web cleaning device shown in FIG. 1 is that, as the supply of the web cleaning material exits through the opening, there is a tendency of the core 13 to be moved into the opening in the U-shaped structure, causing more than one wrap or ply of the fabric to exit at the same time, which eventually leads to binding. This binding leads to a failure of further indexing of the web cleaning material from the supply spool or bobbin and a bowing on the take-up spool that can be permanently damaged.